CN111364475B - Construction method of grouting floral tube anchor rod in soft soil slope support - Google Patents
Construction method of grouting floral tube anchor rod in soft soil slope support Download PDFInfo
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- CN111364475B CN111364475B CN202010209329.4A CN202010209329A CN111364475B CN 111364475 B CN111364475 B CN 111364475B CN 202010209329 A CN202010209329 A CN 202010209329A CN 111364475 B CN111364475 B CN 111364475B
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/02—Foundation pits
- E02D17/04—Bordering surfacing or stiffening the sides of foundation pits
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D33/00—Testing foundations or foundation structures
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/74—Means for anchoring structural elements or bulkheads
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Abstract
The invention discloses a construction method of a slip casting perforated pipe anchor rod in soft soil slope support, which is characterized in that the anchor rod steel bar is fixed in the perforated pipe anchor rod through a combined structure of the perforated pipe anchor rod and the anchor rod steel bar of the slip casting perforated pipe anchor rod by adopting an anchor rod fixing support and a perforated pipe fixing support, and secondary slip casting is carried out through double slip casting holes to ensure the gripping force of a cement column after mud solidification; strengthening the soil strength of the side slope; through the secondary spray anchor, make stock reinforcing bar, concrete spout the layer and form combined action's system with the side slope, prevent and treat that the side slope is not hard up, the separation, stabilize the side slope, but the terminal formula steel sheet that expands of floral tube stock guarantees to spout the layer large tracts of land contact with reinforcing bar net piece and concrete, and reinforced structure face and aspect improve the wholeness and the self-supporting ability of side slope more effectively, restrain the development of warping. The method has the advantages of strong feasibility, low cost, good safety and stability, and remarkable anti-pulling effect in the soft soil area, effectively solves the problem of great influence of soil properties, provides effective anti-pulling force for the soft soil slope, and is suitable for popularization and application.
Description
Technical Field
The invention belongs to the field of building construction, and particularly relates to a construction method of a slip casting perforated pipe anchor rod in soft soil slope support.
Background
As an important form of geotechnical reinforcement, anchor bolt support has the advantages of safety, high efficiency, low cost and the like, and the superiority of anchor bolt support is more and more recognized and is more and more applied in the field of international geotechnical engineering. However, the anchor bolt support also has its limitations, mainly manifested in that it is greatly affected by the soil properties, and when the soil layer is weak, it cannot provide effective uplift resistance. Therefore, the application of the technology is limited to a great extent in poor soil such as high underground water level, mucky soil and the like.
The grouting floral tube anchor rod support is generated under the background, belongs to one of foundation pit support systems, and is characterized in that cement grout enters pores or cracks of a rock-soil body in a permeation or splitting mode through pressure, and the physical and mechanical performance indexes of the rock-soil body can be effectively improved through the gelling and curing effects of the cement grout, so that the strength of the rock-soil body is improved; after grouting is finished, the perforated pipes are kept in the rock-soil layer, so that the effect of reinforcing the rib body can be achieved, and the bearing capacity and the anti-sliding capacity of the rock-soil layer are improved.
The slip casting perforated pipe anchor bolt support is developed based on pure anchor bolt support, makes use of the advantages of other supports to make up the defects of pure anchor bolt support, and simultaneously keeps a plurality of advantages of anchor bolt support. The two functions are combined to effectively improve the safety and stability coefficient of the side slope. The anchoring and supporting problem of the pit wall of the weak soil foundation such as miscellaneous filling soil, silt (or muddy) soil, soft clay, sandy soil and the like is well solved, and the overall stability of the foundation pit supporting system is improved.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a construction method of a slip casting floral tube anchor rod in soft soil slope support.
In order to achieve the purpose, the construction method of the grouting floral tube anchor rod in the soft soil slope support is characterized by comprising the following steps: the method comprises the following steps:
1) excavating a foundation pit and treating a slope surface;
2) drilling and positioning;
3) grouting a floral tube anchor rod to form a hole;
4) manufacturing a grouting floral tube anchor rod;
the inner part of the floral tube anchor rod is used for fixing the anchor rod reinforcing steel bars in the floral tube anchor rod through the anchor rod fixing support, the outer part of the floral tube anchor rod is used for welding the floral tube fixing support on a grout outlet hole of the floral tube anchor rod to form barbs, and the structure of the grouting floral tube anchor rod is formed together;
5) inserting a grouting floral tube anchor rod;
6) grouting the anchor rod of the perforated pipe for the second time;
7) grouting the perforated pipe anchor rod for one-time anchor spraying;
8) binding a steel mesh flower tube outer anchor;
9) grouting the anchor rod of the perforated pipe for secondary anchor spraying;
10) maintaining the grouting floral tube anchor rod;
11) after the construction of the grouting anchor rod with the perforated pipe is finished, carrying out a pulling resistance detection test;
under the same condition, the test quantity is not less than 1% of the total quantity; the number of tests is not less than 3, and a characteristic value of the vertical uplift bearing capacity which is 1.3 times that of the tests is taken;
12) and (5) monitoring the foundation pit.
As a preferred scheme, the step 1) excavation of the foundation pit and slope surface treatment: after mechanical excavation, a 20cm protective layer needs to be reserved, and the slope surface is trimmed manually; before supporting, loose soil must be removed;
step 2) drilling positioning: the allowable deviation of the positioning of the anchor rod hole of the grouting perforated pipe is +/-15 mm; the hole pitch error of the anchor rod is not more than 150 mm;
and 3) grouting a perforated pipe anchor rod to form a hole: the grouting floral tube anchor rod pore-forming requirement is as follows: the drilling hole is round and straight, and the drilling direction is vertical to the main structural surface of the rock stratum as much as possible; the aperture is 15mm larger than the diameter of the rod body; the allowable deviation of the hole depth is +/-50 mm; cleaning the holes must be performed according to relevant regulations;
and 4) manufacturing a grouting floral tube anchor rod:
grouting a floral tube anchor rod: the anchor rod material is phi 20-HRB 400-grade steel bar, and fy is 360 MPa; the anchor rod of the flower tube is a seamless steel tube with phi 48 x 3.0mm, the model Q345; welding rods: model E50 for welding; the rest materials adopt HPB300 grade steel bar, fy is 270MPa, Q235 steel, and E43 type welding rod is used;
step 5), inserting a grouting floral tube anchor rod:
the anchor rod reinforcing steel bar is fixed in the floral tube anchor rod, the tail part of the grouting floral tube anchor rod is jacked by the air compressor, the grouting floral tube anchor rod is uniformly and forcefully vibrated and driven into the air, and the effective anchoring section is deeply inserted into the side slope; the anchor rod fixing support is used for ensuring the accurate position of the anchor rod reinforcing steel bar, and the anchor rod fixing support is used for ensuring the stable structure of the grouting perforated pipe anchor rod; the anchor rod fixing support is made of steel bars with the length of 3 mm and 6 mm, and a group of steel bars is arranged every 2m along the anchor rod;
the floral tube fixing bracket is formed by welding a small-aperture steel tube on a grout outlet hole of a grouting floral tube anchor rod to form an agnail, so that the stable combination of the floral tube anchor rod and a side slope can be ensured, cement mortar can be ensured to permeate into cracks or pores of the side slope, the physical and mechanical property index of a soil body is improved, and the strength of the soil body is improved; the floral tube fixing support is made of a steel tube with the length of 3 phi 8 and the length of 50mm, and a group of floral tubes is arranged at intervals of 500mm along the floral tube.
Further, the step 6) is to perform secondary grouting on the grouting flower tube anchor rod:
after the grouting floral tube anchor rod is formed into a hole, immediately mounting and grouting, performing grouting twice, wherein grouting is performed to an L/2 position for the first time, and grouting is performed to a grouting floral tube anchor rod blocking section for the second time; the grouting pressure is controlled between 0.4 and 0.6Mpa, and the grouting pressure is controlled to be low and high sequentially; in order to ensure sufficient filling rate and not to damage the existing supporting structure, the amount of the single-hole injected cement is more than or equal to 1.5t in principle, the accelerator is added and injected as much as possible until the grouting stopping standard occurs, namely, the non-plugging overflowed slurry occurs;
performing pressure grouting by using M20 cement mortar; the cement is ordinary Portland cement which is not lower than 42.5 grade and has chemical stability for resisting water erosion, and an expansion anti-cracking agent is doped in the ordinary Portland cement to replace the same amount of cement;
cleaning holes before grouting the grouting floral tube anchor rod, and discharging accumulated water in the holes; the grouting pipe and the grouting floral tube anchor rod are simultaneously placed into the hole, the distance from the end of the primary grouting pipe to the bottom of the hole is 100mm, the secondary grouting pipe is provided with a hole with the diameter phi of 3 phi 5@700 within the range of L/2 from the bottom, and the hole and the bottom are firmly tied by using engineering adhesive tapes.
Further, the step 9) of grouting the floral tube anchor rod for secondary anchor spraying:
c20 concrete is sprayed, and the thickness of sprayed layer concrete reaches H/2 and is not less than 20cm when the anchor is sprayed for one time; after the reinforcing mesh is laid and the perforated pipe is anchored outside, spraying concrete for the second time to the designed thickness; when spraying, the spray head is perpendicular to the sprayed surface, and the distance is 0.6-1.2 m; the anchor rod, the concrete sprayed layer and the side slope form a combined action system, so that the side slope is prevented from loosening and separating, and the side slope is stabilized.
Further, after the construction of the grouting floral tube anchor rod in the step 11) is completed, a pullout resistance detection test is performed:
under the same condition, the test quantity is not less than 1 percent of the total quantity, the test quantity is not less than 3, and a characteristic value of the vertical uplift bearing capacity which is 1.3 times that of the total quantity is taken; and after the construction of the grouting floral tube anchor rod is finished, carrying out an acceptance test when the strength of the anchoring body reaches 75% of the designed strength grade.
Further, the step 12) pit monitoring:
the foundation pit monitoring is to monitor the stress deformation of a foundation pit support system and the deformation condition of the surrounding environment, and the detection and distribution points of the foundation pit engineering are as follows:
a. monitoring projects are roads around the foundation pit; the number of the monitoring points is 2 monitoring points of each monitoring section; the monitoring method is measurement by a geometric level; the monitoring precision is that the error in the elevation of the monitoring point is less than 0.15 mm;
B. monitoring items are horizontal and vertical displacements of the top of the supporting structure; the number of the monitoring points is that the monitoring points are arranged on the pile top, and the horizontal distance is less than 30 m; the monitoring method can adopt a sight line method, a small angle method and a point throwing method; the monitoring precision is that the error in the coordinate is less than 1 mm.
Further, the structure of the slip casting flower tube anchor rod is as follows:
by the floral tube stock that anchor section, slip casting section, jam section and outer anchor section constitute, inside fixes the stock reinforcing bar in the floral tube stock through the stock fixed bolster, and the outside welds the floral tube fixed bolster on the grout outlet hole of floral tube stock, forms the barb, constitutes slip casting floral tube stock jointly.
Furthermore, the concrete laying of the reinforcement net in the grouting floral tube anchor rod secondary spray anchor in the step 9) is as follows:
the reinforcing mesh mainly prevents falling rocks or shrinkage cracks of the concrete sprayed layer, improves the integrity of the supporting structure, enables the stress in the concrete sprayed layer to be uniformly distributed and enhances the anti-seismic, anti-shearing and tensile capabilities of the concrete sprayed layer;
the reinforcing mesh is formed by paving phi 8@200X200mm, and the lap joint length is 300 mm; uniformly distributing the anchor rods around the slip casting perforated pipe anchor rods, externally expanding the outer anchor sections of the perforated pipe anchor rods into arch shapes by using an external expander, bending the arch shapes back to the concrete layer, and welding the arch shapes with the reinforcing mesh to ensure the firmness of the reinforcing mesh; and the reinforcing mesh is guaranteed not to shake during anchor spraying.
The working principle of the invention is as follows:
the invention fixes the anchor rod reinforcing steel bars in the grouting floral tube anchor rods, extends the effective anchoring sections into the side slopes, and improves the integral stability of the foundation pit supporting system by methods of secondary grouting, reinforcing mesh, anchor spraying and the like. The anchor rod fixing support is used for guaranteeing the accuracy of the position of the anchor rod reinforcing steel bar, and the anchor rod fixing support is used for guaranteeing the stability of the grouting perforated pipe anchor rod structure. The method adopts M20 cement mortar for pressure grouting, and is internally doped with an expansion crack-resistant agent (replacing equal amount of cement), thereby being the best method for saving energy and reducing cost. The grouting floral tube anchor rod is adopted, and the construction of the anchoring section is simple and convenient; the grouting section adopts secondary grouting to ensure the gripping force of the cement column after the slurry is solidified; when the mortar overflows from the orifice, the blocking section blocks the mortar to prevent the mortar from leaking; the expandable steel sheet of the outer anchor section can be ensured to be in large-area contact with the reinforcing mesh and the concrete sprayed layer, the structural surface and the bedding surface are reinforced, the integrity and the self-supporting capability of the side slope are effectively improved, and the development of deformation is inhibited. The floral tube fixing support is formed by welding a small-aperture steel tube on a grout outlet hole of a grouting floral tube anchor rod to form an agnail, so that the stable combination of the floral tube anchor rod and a side slope can be ensured, cement mortar can be ensured to permeate into cracks or pores of the side slope, the physical and mechanical property index of a soil body is improved, and the strength of the soil body is improved. The reinforcing mesh mainly prevents falling rocks or shrinkage cracks of the concrete sprayed layer, improves the integrity of the supporting structure, enables the stress in the concrete sprayed layer to be uniformly distributed and enhances the capabilities of resisting earthquake, shearing and tension of the concrete sprayed layer. The anchor rod, the concrete spraying layer and the side slope form a combined action system through secondary spraying anchor, so that the side slope is prevented from loosening and separating, and the side slope is stabilized. The invention has the advantages of simple and convenient operation, strong feasibility, short construction period, low cost, better safety and stability, ingenious design, reasonable form and obvious uplift resistance effect in the soft soil area, better solves the problem of great influence by the soil property, provides effective uplift resistance for the soft soil side slope and is suitable for popularization and application.
The invention has the following advantages and beneficial effects:
according to the construction method for supporting the slip casting perforated pipe anchor rod on the soft soil side slope, the anchor rod steel bar is fixed in the perforated pipe anchor rod through the combination structure of the perforated pipe anchor rod and the anchor rod steel bar of the slip casting perforated pipe anchor rod by adopting the anchor rod fixing support and the perforated pipe fixing support, and the slip casting perforated pipe anchor rod is fixed in the side slope, so that the position is accurate, and the structure is firm; the gripping force of the cement column after the slurry is solidified is ensured through secondary grouting, and the soil body strength of the side slope is strengthened; through secondary spray anchoring, the anchor rod reinforcing steel bars, the concrete spray layer and the side slope form a combined action system, so that the side slope is prevented from loosening and separating, and the side slope is stabilized. The method has the advantages of simple and convenient operation, strong feasibility, short construction period, low cost, good safety and stability, ingenious design, reasonable form and obvious underground anti-floating effect, and is suitable for popularization and application.
The main innovation points of the invention are as follows:
(1) the invention adopts the anchor rod reinforcing steel bars 1 to be fixed in the grouting floral tube anchor rods 12, the effective anchoring sections 3 are deeply inserted into the side slope, and the overall stability of the foundation pit supporting system is improved by methods of secondary grouting, reinforcing mesh 11, anchor spraying and the like.Ensure waterproof concrete And (4) cracking resistance.
(2) The anchor rod fixing bracket 2 is connected with the anchor rod reinforcing steel bar 1 in a welding mode, the anchor rod fixing bracket 2 is used for ensuring the position accuracy of the anchor rod reinforcing steel bar 1,and the anchor rod fixing bracket 2 is utilized to ensure the stable structure of the grouting floral tube anchor rod 12.
(3) The perforated pipe fixing support 7 is connected with the grouting perforated pipe anchor rod 12 in a welding mode, and a group of the grouting perforated pipe anchor rod is arranged along the grouting perforated pipe anchor rod 12 every 500 mm.Utilize floral tube fixed bolster 7 to ensure slip casting floral tube stock 12 and slope stable in structure, improve soil Bulk strength.
(4) The reinforcing mesh 11 is adopted to mainly prevent falling rocks or concrete spray coating shrinkage cracks, improve the integrity of the supporting structure,the stress in the concrete spraying layer is uniformly distributed, and the shock resistance, shear resistance and tensile resistance of the concrete spraying layer are enhanced.
(5) M20 cement mortar is used for pressure grouting, and an expansion crack-resistant agent (instead of equal amount of cement) is doped in the mortar.Is energy-saving and can reduce The best method with low cost.
(6) By usingThe secondary spray anchor enables the grouting perforated pipe anchor rod 12, the concrete spray layer and the side slope to form a combined action system.Is that Preventing and controlling the loosening and separation of the side slope and stabilizing the side slope.
(7) The outer anchor section 6 of the grouted perforated pipe anchor rod is arched and bent back to the concrete sprayed layer by using an external expander, and is welded with the reinforcing mesh 11.The reinforcing mesh 11 is ensured to be firm, the energy is saved, and the cost is reduced.
(8) After the construction is finished, the uplift resistance is detected, and a characteristic value of the vertical uplift bearing capacity which is 1.3 times that of the construction is taken.Is to ensure grouting Stability of the structure of the floral tube anchor 12.
Drawings
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is a pictorial view of a bolt of the present invention;
FIG. 3 is a schematic view of a grouting floral tube anchor rod of the present invention;
FIG. 4 is a cross-sectional view of the floral tube anchor of the present invention;
fig. 5 is a schematic view of the reinforcing mesh of the present invention;
fig. 6 is a construction drawing of an outer anchor section of the grouting floral tube anchor rod of the invention.
In the figure: 1-anchor bar reinforcing steel bars, 2-anchor bar fixing supports, 3-anchoring sections, 4-grouting sections, 5-blocking sections, 6-outer anchor sections, 7-perforated pipe fixing supports, 8-primary grouting holes, 9-secondary grouting holes, 10-perforated pipe anchor bars, 11-reinforcing mesh, 12-grouting perforated pipe anchor bars, 13-C20 concrete, m-horizontal spacing and H-concrete thickness.
Detailed Description
The invention is further described in detail below with reference to the figures and specific examples.
The construction method of the grouting floral tube anchor rod in the soft soil slope support comprises the following steps: the anchor rod 10 (anchoring section 3, grouting section 4, blocking section 5, outer anchoring section 6), anchor rod reinforcing steel bars, anchor rod fixing support 2, reinforcing mesh 11, M20 cement mortar pressure secondary grouting, secondary shotcrete, anchor rod fixing support 7, primary grouting pipe, secondary grouting pipe, concrete spray layer and the like.
The method specifically comprises the following steps:
1) excavation of a foundation pit, slope treatment: after mechanical excavation, a 20cm protective layer needs to be reserved, and the slope surface is trimmed manually; before supporting, loose soil must be removed.
2) The construction process flow of the grouting floral tube anchor rod 12 (detailed figure 1).
3) The allowable deviation of the hole position location of the grouting floral tube anchor rod 12 is +/-15 mm; the bolt hole pitch error is not more than 150 mm.
4) Grouting the hole forming requirement of the anchor rod 12 of the floral tube: the drilling hole is round and straight, and the drilling direction is vertical to the main structural surface of the rock stratum as much as possible; the aperture is 15mm larger than the diameter of the rod body; the allowable deviation of the hole depth is +/-50 mm; cleaning of the holes must be performed as specified.
5) Grouting a floral tube anchor rod 12: the anchor rod material is phi 20-HRB 400-grade steel bar, and fy is 360 MPa; the material of the flower tube anchor rod 10 is a seamless steel tube with phi 48 x 3.0mm, the model Q345; welding rods: model E50 is used for welding. The rest of the materials were HPB300 grade steel bar (fy 270MPa), Q235 steel, using E43 type welding rod.
6) The anchor rod reinforcing steel bars are fixed in the perforated pipe anchor rod 10, the effective anchoring sections 3 are deeply inserted into the side slope, and the overall stability of the foundation pit supporting system is improved through methods of secondary grouting, reinforcing mesh 11, anchor spraying and the like.
7) The anchor rod fixing bracket 2 is used for ensuring the accurate position of the anchor rod reinforcing steel bar, and the anchor rod fixing bracket 2 is used for ensuring the stable structure of the floral tube anchor rod 10. The anchor rod fixing support 2 is made of steel bars with the length of 3 phi 6 mm and the length of 600mm, and a group of steel bars is arranged every 2m along the anchor rod.
8) The floral tube fixing support 7 is formed by welding a small-aperture steel tube on a grout outlet of the floral tube anchor rod 10 to form barbs, so that the stable combination of the floral tube anchor rod 10 and a side slope can be ensured, cement mortar can be ensured to permeate into cracks or pores of the side slope, the physical and mechanical property index of a soil body is improved, and the strength of the soil body is improved.
9) The floral tube fixing bracket 7 is made of a steel tube with the length of 3 phi 8 and the length of 50mm, and a group of floral tubes is arranged every 500mm along the floral tube.
10) And (3) performing secondary grouting on the grouting anchor rod 12 by using M20 cement mortar for pressure grouting. The cement is ordinary Portland cement which is not lower than 42.5 grade and has chemical stability for resisting water erosion, and is internally doped with an expansion anti-cracking agent (replacing equivalent cement), so that the cement is the best method for saving energy and reducing cost.
11) Cleaning holes before grouting the grouting floral tube anchor rod 12, and discharging accumulated water in the holes; the grouting pipe and the anchor rod 10 are preferably put into the hole at the same time, the distance from the end of the primary grouting pipe to the bottom of the hole is preferably 100mm, and the secondary grouting pipe is provided with a hole within the range of L/2 from the bottom
And the eyelet and the bottom are firmly tied by using an engineering adhesive tape. After the grouting floral tube anchor rod 12 is formed into a hole, the installation and grouting are carried out immediately, the grouting is carried out twice, the grouting is carried out to the L/2 position for the first time, and the grouting is carried out to the grouting floral tube anchor rod blocking section 5 for the second time.
12) And (3) spraying C20 concrete for the secondary spray anchor of the grouting perforated anchor rod 12, wherein the thickness of sprayed layer concrete reaches H/2 (not less than 20) during the primary spray anchor, and spraying the second concrete to the designed thickness after the reinforcing mesh 11 is laid and the perforated pipe is anchored outside. When spraying, the spray head and the sprayed surface should be vertical, and the distance is preferably 0.6-1.2 m.
13) The reinforcing mesh 11 mainly prevents falling rocks or shrinkage cracks of the concrete sprayed layer, improves the integrity of the supporting structure, enables the stress in the concrete sprayed layer to be uniformly distributed and enhances the anti-seismic, anti-shearing and tensile capabilities of the concrete sprayed layer.
14) The reinforcing mesh 11 is laid by phi 8@200X200mm, and the lap joint length is 300 mm; and the outer anchor components of the perforated pipe are bent into an arch shape by an external expander and then are bent back to the concrete layer and are welded with the reinforcing mesh 11; the reinforcing mat 11 is secured.
15) The anchor rod, the concrete spraying layer and the side slope form a combined action system by secondary spraying anchor, so as to prevent and control the side slope from loosening and separating and stabilize the side slope
16) And (3) after the construction of the grouting floral tube anchor rod 12 is finished, the uplift resistance detection is carried out, under the same condition, the test quantity is not less than 1 percent of the total quantity, the test quantity is not less than 3, and a characteristic value of the vertical uplift resistance bearing capacity of 1.3 times is taken. After the construction of the grouting floral tube anchor rod 12 is finished, when the strength of the anchoring body reaches 75% of the designed strength grade, an acceptance test is required.
17) The foundation pit monitoring is to monitor the stress deformation of the foundation pit enclosure system and the deformation of the surrounding environment, and is shown in the following table:
foundation pit engineering detection and distribution table
Application example: the method is successfully applied to the international (first-term) price-limiting commodity (arrangement) house project of HL in H county of J province.
H county HL international (first-stage) price-limiting commodity (placement) house project is located at the south bank of the middle and lower reaches of Yangtze river and at the side of Poyang lake north, and the water level and the water quantity are greatly influenced by seasonal changes. During continuous rainfall or rainstorm, the water level can be basically kept level with the outdoor terrace when being highest, and the effective uplift resistance can not be provided by adopting the conventional anchor rod support, so the grouting floral tube anchor rod 12 is adopted. Fixing the anchor rod reinforcing steel bars in the perforated pipe anchor rod 10 by adopting an anchor rod fixing support 2 and a perforated pipe fixing support 7 through a perforated pipe anchor rod 10 and anchor rod reinforcing steel bar combination structure of a grouting perforated pipe anchor rod 12, and performing secondary grouting through double grouting holes to ensure the gripping force of the cement column after the slurry is solidified; strengthening the soil strength of the side slope; through the secondary spray anchor, make stock reinforcing bar, concrete spout the layer and the side slope forms combined action's system, the prevention and cure side slope is not hard up, the separation, and the side slope is stabilized, and the floral tube end can expand the formula steel sheet and guarantee to spout the layer large tracts of land contact with reinforcing bar net piece 11 and concrete, reinforced structure face and aspect, the wholeness and the self-supporting ability of more effectual improvement side slope restrain the development of warping.
Claims (4)
1. A construction method of a slip casting perforated pipe anchor rod in soft soil slope support is characterized in that: the method comprises the following steps:
1) excavating a foundation pit and treating a slope surface;
2) drilling and positioning;
3) grouting a floral tube anchor rod (12) to form a hole;
4) manufacturing a grouting floral tube anchor rod (12);
the grouting anchor rod comprises a floral tube anchor rod (10) consisting of an anchoring section (3), a grouting section (4), a blocking section (5) and an outer anchoring section (6), wherein an anchor rod reinforcing steel bar (1) is fixed in the floral tube anchor rod (10) through an anchor rod fixing support (2) at the inner part of the floral tube anchor rod, and a floral tube fixing support (7) is welded on a grout outlet hole of the floral tube anchor rod (10) at the outer part of the floral tube anchor rod to form barbs, so that a structure of the grouting floral tube anchor rod (12) is formed;
5) inserting a grouting floral tube anchor rod (12);
6) grouting the anchor rod (12) of the perforated pipe for the second time;
7) primary anchor spraying of the grouting floral tube anchor rod (12);
8) firstly, binding a reinforcing mesh (11), and then anchoring an outer anchor section (6) of the floral tube anchor rod (10) on the reinforcing mesh (11);
9) grouting a perforated pipe anchor rod (12) for secondary anchor spraying;
10) maintaining the grouting anchor rod (12) of the floral tube;
11) after the construction of the grouting anchor rod (12) of the perforated pipe is finished, carrying out an anti-pulling force detection test;
under the same condition, the test quantity is not less than 1% of the total quantity; the number of tests is not less than 3, and a characteristic value of the vertical uplift bearing capacity which is 1.3 times that of the tests is taken;
12) monitoring a foundation pit;
step 1) excavation of foundation pit, slope surface treatment: after mechanical excavation, a 20cm protective layer needs to be reserved, and the slope surface is trimmed manually; before supporting, loose soil must be removed;
step 2) drilling positioning: the allowable deviation of the hole position location of the grouting floral tube anchor rod (12) is +/-15 mm; the hole pitch error of the anchor rod is not more than 150 mm;
step 3), grouting a perforated pipe anchor rod (12) to form a hole: the grouting floral tube anchor rod (12) meets the pore-forming requirement: the drilling hole is round and straight, and the drilling direction is vertical to the main structural surface of the rock stratum as much as possible; the aperture is 15mm larger than the diameter of the rod body; the allowable deviation of the hole depth is +/-50 mm; cleaning the holes must be performed according to relevant regulations;
and 4) manufacturing a grouting floral tube anchor rod (12):
grouting a floral tube anchor rod (12): the anchor rod material is phi 20-HRB 400-grade steel bar, and fy is 360 MPa; the material of the flower tube anchor rod 10 is a seamless steel tube with phi 48 x 3.0mm, the model Q345; welding rods: model E50 for welding; the rest materials adopt HPB300 grade steel bar, fy is 270MPa, Q235 steel, and E43 type welding rod is used;
step 5), inserting a grouting flower tube anchor rod (12):
the anchor rod reinforcing steel bars (1) are fixed in the perforated pipe anchor rod (10), the tail part of the grouting perforated pipe anchor rod (12) is propped by the connection of an air compressor, the grouting perforated pipe anchor rod is uniformly and forcefully vibrated and driven into the air, and the effective anchoring section (3) is deeply inserted into a side slope; the anchor rod fixing support (2) is used for ensuring the accurate position of the anchor rod reinforcing steel bar (1), and the anchor rod fixing support (2) is used for ensuring the stable structure of the grouting perforated pipe anchor rod (12); the anchor rod fixing support (2) is made of steel bars with the diameter of 3 phi 6 and the length of 600mm, and a group of steel bars is arranged every 2m along the anchor rod steel bars (1);
the floral tube fixing bracket (7) is formed by welding a small-aperture steel tube on a grout outlet of a grouting floral tube anchor rod (12) to form barbs, so that the stable combination of the floral tube anchor rod (10) and a side slope can be ensured, cement mortar can be ensured to permeate into cracks or pores of the side slope, the physical and mechanical property index of a soil body is improved, and the strength of the soil body is improved; the floral tube fixing support (7) is made of steel tubes with the diameter of 3 phi 8 and the length of 50mm, and one group of floral tube fixing supports is arranged along the floral tube every 500 mm;
and 6), grouting for the second time by using a perforated pipe anchor rod (12):
after the grouting floral tube anchor rod (12) is formed into a hole, immediately mounting and grouting, performing grouting twice, wherein grouting is performed to an L/2 position for the first time, and grouting is performed to a grouting floral tube anchor rod blocking section (5) for the second time; the grouting pressure is controlled between 0.4 and 0.6Mpa, and the grouting pressure is controlled to be low and high sequentially; in order to ensure sufficient filling rate and not to damage the existing supporting structure, the amount of the single-hole injected cement is more than or equal to 1.5t in principle, the accelerator is added and injected as much as possible until the grouting stopping standard occurs, namely, the non-plugging overflowed slurry occurs;
performing pressure grouting by using M20 cement mortar; the cement is ordinary Portland cement which is not lower than 42.5 grade and has chemical stability for resisting water erosion, and an expansion anti-cracking agent is doped in the ordinary Portland cement to replace the same amount of cement;
before grouting, the hole of the grouting floral tube anchor rod (12) is cleaned, and accumulated water in the hole is discharged; the grouting pipe and the grouting anchor rod (12) are simultaneously placed into the hole, the distance from the end of the primary grouting pipe to the bottom of the hole is 100mm, the secondary grouting pipe is provided with a hole with the diameter of 3 phi 5@700 within the range of L/2 from the bottom, and the hole and the bottom are fastened by engineering adhesive tapes;
and 9) grouting a perforated pipe anchor rod (12) for secondary anchor spraying:
c20 concrete is sprayed, and the thickness of sprayed layer concrete reaches H/2 and is not less than 20cm when the anchor is sprayed for one time; after the reinforcing mesh (11) is laid and the perforated pipe is anchored outside, spraying the second-time concrete to the designed thickness; when spraying, the spray head is perpendicular to the sprayed surface, and the distance is 0.6-1.2 m; the anchor rod, the concrete sprayed layer and the side slope form a combined action system, so that the side slope is prevented from loosening and separating, and the side slope is stabilized.
2. The construction method of the slip casting perforated pipe anchor rod in soft soil slope support according to claim 1, characterized in that: and 11), carrying out an anti-pulling force detection test after the construction of the grouting floral tube anchor rod (12) is completed:
under the same condition, the test quantity is not less than 1 percent of the total quantity, the test quantity is not less than 3, and a characteristic value of the vertical uplift bearing capacity which is 1.3 times that of the total quantity is taken; and after the grouting floral tube anchor rod (12) is constructed, performing an acceptance test when the strength of the anchoring body reaches 75% of the designed strength grade.
3. The construction method of the grouting floral tube anchor rod in soft soil slope support according to claim 2, characterized in that: step 12) foundation pit monitoring:
the foundation pit monitoring is to monitor the stress deformation of a foundation pit support system and the deformation condition of the surrounding environment, and the detection and distribution points of the foundation pit engineering are as follows:
a. monitoring projects are roads around the foundation pit; the number of the monitoring points is 2 monitoring points of each monitoring section; the monitoring method is measurement by a geometric level; the monitoring precision is that the error in the elevation of the monitoring point is less than 0.15 mm;
B. monitoring items are horizontal and vertical displacements of the top of the supporting structure; the number of the monitoring points is that the monitoring points are arranged on the pile top, and the horizontal distance is less than 30 m; the monitoring method can adopt a sight line method, a small angle method and a point method; the monitoring precision is that the error in the coordinate is less than 1 mm.
4. The construction method of the slip casting perforated pipe anchor rod in soft soil slope support according to claim 3, characterized in that: the step 9) of laying the reinforcement net (11) in the grouting perforated pipe anchor rod (12) in the secondary spray anchor is as follows:
the reinforcing mesh (11) is mainly used for preventing falling rocks or shrinkage cracks of a concrete sprayed layer, improving the integrity of a supporting structure, enabling the stress in the concrete sprayed layer to be uniformly distributed and enhancing the anti-seismic, anti-shearing and tensile capabilities of the concrete sprayed layer;
the reinforcing mesh (11) is formed by paving phi 8@200X200mm, and the lap joint length is 300 mm; uniformly distributing the slurry around the slip casting perforated pipe anchor rod (12), expanding the outer anchor section (6) of the perforated pipe anchor rod (10) into an arch-shaped bent back mixed concrete layer by using an external expander, and welding the arch-shaped bent back mixed concrete layer with a reinforcing mesh (11) to ensure the firmness of the reinforcing mesh (11); the reinforcing mesh (11) can not shake when the anchor is sprayed.
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